import java.util.*;
public class Alist {

	/**
	 * @param args
	 */

	HashMap<String, Sexpr> alist;
	public Alist()
	{
		 this.alist = new HashMap<String, Sexpr> ();
	}
	public void pushVal(String name, Sexpr sexpr)
	{
		this.alist.put(name, sexpr);		
	}
	public Sexpr getVal(String name)
	{
		Sexpr sexpr = this.alist.get(name);
		return sexpr;
	}
	public Sexpr popSexpr(String name)
	{
		Sexpr sexpr = this.alist.remove(name);
		return sexpr;
	}	
	public static void main(String[] args) {
		// TODO Auto-generated method stub

	}

}
